Remote-control device



Nov. 30, 1954 J. J. HUPERT ETAL ,951

REMOTE-CONTROL DEVICE Original Filed Nov. 29, 1949 INVENTOR-S. My L/l VZ veWZ" Md aawzzw United States Patent M REMOTE-CONTROL DEVICE Julius J. Hupert, Glen Ellyn, and 'Riehard Goldstein, Des Plaines, Ill., assignors to A. R. F. Products, Inc., River Forest, "Ill., a corporation of Illinois Original application November 29, 1949, Serial No. 130,061. :qDivided and: this application'May 9, 1952, Serial No. 286,957

1 .Claim. (Cl. 250-17) This invention is concerned with a transmitting device operable in cooperation with a receiving device for controlling garage doors from a remote location. The present application is a division of our application Serial No. 130,061 filed November 29, 1949, and entitled Remote Control Device, that application being in turn a continuation-in-part of our application Serial No. 47,886, filed September 4, 1948, entitled Remote Control Device, and which has now become abandoned.

Various types of remote control devices have been used in the past and have been found wanting. These devices include radio communication devices operating on conventional radio frequencies, microwave devices, electromagnetic induction devices without an electronic amplifier, supersonic sound devices, audio sound devices, and photocell devices.

A radio communication device has the dual disadvantage of difficulties in complying with Federal Communications Commission regulations and of being particularly susceptible to electrical disturbances. Electronic devices for scientific, industrial and medical use, as well as other electrical disturbances, both natural and man-made, often cause the garage doors to open and close at random.

Microwave devices are generally not quite so susceptible to electrical disturbance as such disturbance is more common in the lower ranges of the frequency spectrum, but these devices are expensive to manufacture. Occasional long distance transmission phenomena which are quite unpredictable cause radio frequency energy to be transmitted abnormal distances and this energy then opens the garage doors of other parties living at considerable distances but operating on the same frequency.

Previous electromagnetic induction devices had little use due to the necessarily loose coupling between the primary and secondary coils which not only severely limited the range of operation and caused a large power loss, but made it necessary for the driver of the car to painstakingly orient the car so that the primary coil in the car would be positioned directly over the secondary coil buried in the driveway.

A supersonic sound system operates at a frequency near enough to audio frequencies that it is very diflicult to discriminate against the audio frequencies and spurious operation will be encountered. Furthermore, there are many devices (such as whistles for calling dogs) that operate in the supersonic range and will cause unwanted opening and closing of the garage doors.

Audio sound devices have the same faults as supersonic devices to a greater degree as well as presenting an objectionable noise.

A photo-cell device is relatively dependable in operation but requires that a light beam be aimed at a photocell across the driveway. Besides the necessity of an original adjustment, both the light source and the photocell are easily misaligned by accidental bumps. A greater objection is that a photo-cell device is non-selective and will respond to anything interrupting the light beam and will thus cause the garage door to open or close at frequent undesired times. Children particularly enjoy operating photo-cell devices and many children are so inquisitive or wanton as to damage the equipment. Furthermore, it is easy for thieves to open the garage door to remove the car or other articles.

This invention contemplates the use of a low radio frequency carrier on the order of 50,000 to 300,000 cycles per second modulated by a low audio frequency signal 2,695,951 Patented Nov. 30, 1954 for unpredictable distances as are electrostatic waves.

Thus, operation of a garage door by the wrong transmitting device is avoided.

Applicants use of a low audio frequency to modulate the low radio frequency carrier makes the percentage frequency swing relatively small and receiving circuits therefore can be made quite selective.

For automotive use it will be apparent that a transmitting device should occupy a minimum of space and that the electric power required should be as small as possible.

An object of this invention is to provide a batterypowered transmitter for the remote control of garage doors and the like wherein the transmitter establishes a carrier wave modulated by a vibrator in the power supply of the transmitter.

Another object of this invention is to provide a transmitter utilizing a self-rectifying oscillator powered by a battery and vibrator unit wherein the vibrator unit is unfiltered so as to modulate the carrier wave with the vibrator frequency.

A further object of this invention is to provide a transmitter utilizing an unfiltered vibrator power supply whereby to modulate the carrier wave with the vibrator frequency, and wherein an oscillator tank circuit coil is utilized for propagating an induction field wave, said transmitter being free from the conventional radiating antenna.

We have found that the use of a 90 cycle per second vibrator is particularly desirable. The 90 cycle per second audio frequency is sufficiently far removed from the low radio freqeuncy of 50300 kilocycles per second to allow sharply selective tuning. Furthermore, the 90 cycle per second frequncy avoids the fundamentals and harmonics of the usual 60 cycle per second power transmission lines and the sometimes found 25 cycles per second power transmission lines.

The objects enumerated and further objects and advantages will be readily understood from the following description when taken in connection with the accom- 'panying drawing which is a schematic wiring diagram of the transmitter.

The transmitter shown in the figure is powered by a six-volt automobile battery indicated by the arrow connected to the switch 10 and a vibrator 12. The vibrator 1s provided with a vibrating contact 14 which is grounded through a radio frequency choke 16. A pair of fixed contacts 18 are alternately contacted by the vibrating contact 14 and are connected to the extremities of the primary winding 20 of a transformer 22. The actuating magnet 23 is connected conventionally between the vibrating contact 14 and one of the fixed contacts 18. A center tap 24 on the primary winding is connected to the switch 10 and also to the filament 26 of an oscillator tube 28, the other side of the filament being grounded The secondary winding 32 of the transformer 22 is paralleled by a capacitor 34 and the parallel combination is grounded at one end at 36. The other end is connected through a radio frequency choke 38 to the center tap 40 of the tank circuit of the oscillator 44. The

oscillator may be any of several desirable types and one of the Colpitts type has been chosen for illustration.

The oscillator 44 is of the well known self-rectifying type, and the radio frequency signal generated by the oscillator is modulated by the fluctuating plate supply voltage. The plate supply voltage fluctuates at the frequency of the vibrator due to the lack of any filter or rectifier on the output of the transformer 22.

No conventional radiating antenna is provided, and

30 the radiation field therefore is negligible. The induction field from the inductance coil of the tank circuit 42 gives the highest possible ratio of induction to radiation field.

It will be seen that the transmitter shown meets the objects of the invention and can be constructed so as to be quite rugged and so as to occupy a minimum of space. The particular example shown is for illustrative purposes, and it will be understood that our invention includes all that which falls fairly within the spirit and scope of the appended claim.

We claim:

A transmitter for the remote control of garage doors and the like comprising a source of low voltage direct current, a vibrator including a fixed contact and a cooperating vibrating contact, means including a coil for causing said vibrating contact to vibrate, a transformer having a primary Winding and a secondary Winding, said fixed contact and said source of current being connected to said primary winding at spaced apart points and said vibrating contact being connected to ground through a reactance, a capacitor connected across said secondary winding, one end of said secondary winding being grounded, a first inductance having one end thereof connected to the other end of said secondary winding, an electron tube having a cathode and control grid and anode, an oscillator tank circuit including a second inductance in parallel with a capacitance, one end of said second inductance being connected to said anode, a capacitor connecting the other end of said second inductance to said control grid, an impedance interconnecting said control grid and said cathode, means for heating said cathode, said heating means including a ground connection, and a connection between the other end of said first inductance and substantially the center of said second inductance, said electron tube and oscillator tank circuit generating a radio frequency carrier wave modulated at the interruption rate of said vibrator, said second inductance serving as an antenna to emit a strong induction field and a relatively weak radiation field of the carrier wave.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 18,971 Rockwell Oct. 24, 1933 1,597,416 Mirick Aug. 24, 1926 1,760,479 Colman May 27, 1930 2,390,489 Archenbronn Dec. 11, 1945 2,475,994 Short July 12, 1949 2,499,912 Gelzer Mar. 7, 1950 2,508,082 Wald May 16, 1950 OTHER REFERENCES Stolen Moneybag Calls Police, Radio & Television Magazine, January 1939, page 522. 

